MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (MALAKAS) WARNING NR 34// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 18W (MALAKAS), LOCATED APPROXIMATELY 113 NM SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHEASTWARD AT 21 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A SYSTEM THAT HAS WEAKENED BUT HAS MAINTAINED RELATIVELY ORGANIZED OVER THE LAST SIX HOURS AS IT HAS SKIRTED THE ISLAND OF SHIKOKU. THE INITIAL POSITION IS BASED ON JMA RADAR FIXES AND SATELLITE FIXES FROM PGTW AND RJTD WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS AND IS BASED ON AN AVERAGE FROM ALL AGENCIES REPORTING DVORAK ESTIMATES RANGING FROM T4.5 TO T3.5 (55 TO 77 KNOTS). A 200100Z OBSERVATION FROM MUROTO-MISAKI, LOCATED NEAR THE TYPHOON CENTER, INDICATED SUSTAINED WINDS FROM THE EAST- SOUTHEAST AT 60 KNOTS. UPPER-LEVEL ANALYSIS SHOWS INCREASING VALUES OF WIND SHEAR ASSOCIATED WITH THE WESTERLY JET AND A SHORTWAVE TROUGH MOVING IN FROM THE NORTHWEST. SEA SURFACE TEMPERATURES ARE FAVORABLE NEAR 28 CELSIUS. CURRENTLY TY MALAKAS IS TRAVELING EAST- NORTHEAST ALONG THE NORTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE LOCATED TO THE SOUTHWEST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY MALAKAS WILL CONTINUE TO TRACK NORTH-NORTHEAST UNDER THE INFLUENCE OF THE CURRENT STEERING RIDGE ALONG THE SHORELINE OF SOUTHERN JAPAN. THE CLOSE PROXIMITY TO LAND WILL DISRUPT THE LOW- LEVEL WIND FLOW THROUGHOUT THE FORECAST PERIOD. THIS IN CONJUNCTION WITH RISING SHEAR VALUES WILL SERVE TO WEAKEN THE SYSTEM. SSTS WILL REMAIN FAVORABLE FOR THE IMMEDIATE FUTURE, BUT AS TY MALAKAS PASSES THE KII PENINSULA, SSTS WILL DROP CONSIDERABLY, CONTRIBUTING TO THE WEAKENING TREND. TY MALAKAS IS FORECAST TO DISSIPATE BY TAU 48. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 24, BUT START TO DIVERGE SOMEWHAT AFTER TY MALAKAS PASSES YOKOSUKA, JAPAN DUE TO A DRASTICALLY WEAKENED SYSTEM, LENDING HIGH CONFIDENCE TO THE FORECAST TRACK.// NNNN NNNN